Optimization on airflow distribution for anti-condensation of high-voltage switchgear using CFD method

Underground garages, indoor stadiums, or more commonly used seagoing ships, can be used as large multi-purpose spaces, which are suitable for the carriage of a wide range of cargoes, as well as evacuation of people at overseas. The indoor environment in a multi-purpose cabin usually varies, in terms of pollutant emissions, hazardous levels and the corresponding ventilation requirements. A possible solution, in addition to a single regular HVAC system, is to use multiple induced jet fans. However, to pre-determine a universal design of fans, e.g., numbers, locations, directions, angles and flowrates, etc., may not be practical. In this preliminary work, methods to design the auxiliary ventilation system were discussed. The heat sources are located in the four corners on the floor. CFD method is used to further study the effects of six regular and four irregular arrangements of a 2×2 array of fans on local heat dilution with or without natural ventilation (e.g., additional openings in the space). Heat exhaust efficiency is used to evaluate the effects of different arrangements of fans on local heat dilution. The results show that adjustable ventilation using induced fans would be useful to provide various airflow distribution for a large space and the dilution of the heat can be improved and the areas of high temperature inside the space can be reduced. Furthermore, the heat exhaust efficiency would be higher and the induced fans have a more significant effect, especially when additional natural ventilation is available.

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Simulation study on effects of purifier positions on formaldehyde removal under the condition of vehicle air supply

Proceedings of the Institution of Mechanical Engineers Part D Journal of Automobile Engineering ◽

10.1177/09544070211054945 ◽

2021 ◽

pp. 095440702110549

Author(s):

Jia Li ◽

Quan Zhang ◽

Xuewen Zhang

Keyword(s):

Air Quality ◽

Concentration Field ◽

Formaldehyde Concentration ◽

Actual Measurement ◽

Air Supply ◽

Airflow Distribution ◽

Formaldehyde Removal ◽

Air Purifier ◽

Simulation Results ◽

Cfd Method

In order to further improve the interior air quality and comfort of the vehicle, CFD method is used to simulate the different airflow distribution caused by car-mounted air purifiers at different positions. Combined with the change of formaldehyde concentration field in car, the influence of car-mounted air purifiers on the formaldehyde dilution and removal under the condition of air conditioning air supply is analyzed. The simulation results are verified by actual measurement, and the trend of the simulation results is basically consistent with the measured results. When the car air purifier placed in the middle of the car roof, it can effectively dilute and purify the formaldehyde gas in the car, and reduce the concentration of formaldehyde in the breathing area of the driver and passengers. The adsorption and degradation of formaldehyde by the purifier, together with the dilution of formaldehyde by air supply, can improve the air quality in cars more effectively than using only one of the air purification methods.

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High Voltage Electron Microscopy of Ion-Milled Dental Enamel

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100050317 ◽

1974 ◽

Vol 32 ◽

pp. 60-61

Author(s):

L. D. Ackerman ◽

S. H. Y. Wei

Keyword(s):

Electron Microscopy ◽

High Voltage ◽

Third Molar ◽

Polarized Light ◽

Dental Enamel ◽

Longitudinal Section ◽

Ion Milling ◽

High Voltage Electron Microscopy ◽

Voltage Electron ◽

High Voltage Electron

Mature human dental enamel has presented investigators with several difficulties in ultramicrotomy of specimens for electron microscopy due to its high degree of mineralization. This study explores the possibility of combining ion-milling and high voltage electron microscopy as a means of circumventing the problems of ultramicrotomy.A longitudinal section of an extracted human third molar was ground to a thickness of about 30 um and polarized light micrographs were taken. The specimen was attached to a single hole grid and thinned by argon-ion bombardment at 15° incidence while rotating at 15 rpm. The beam current in each of two guns was 50 μA with an accelerating voltage of 4 kV. A 20 nm carbon coating was evaporated onto the specimen to prevent an electron charge from building up during electron microscopy.

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Three-Dimensional Visualization of the T-System of Frog Muscle Using High Voltage Electron Microscopy and a Lanthanum Stain

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100080286 ◽

1977 ◽

Vol 35 ◽

pp. 570-571 ◽

Cited By ~ 2

Author(s):

Lee D. Peachey ◽

Clara Franzini-Armstrong

Keyword(s):

Electron Microscopy ◽

High Voltage ◽

Three Dimensional ◽

Biological Tissues ◽

High Voltage Electron Microscopy ◽

Transverse Tubular System ◽

Peroxidase Reaction ◽

Voltage Electron ◽

High Voltage Electron ◽

T System

The effective study of biological tissues in thick slices of embedded material by high voltage electron microscopy (HVEM) requires highly selective staining of those structures to be visualized so that they are not hidden or obscured by other structures in the image. A tilt pair of micrographs with subsequent stereoscopic viewing can be an important aid in three-dimensional visualization of these images, once an appropriate stain has been found. The peroxidase reaction has been used for this purpose in visualizing the T-system (transverse tubular system) of frog skeletal muscle by HVEM (1). We have found infiltration with lanthanum hydroxide to be particularly useful for three-dimensional visualization of certain aspects of the structure of the T- system in skeletal muscles of the frog. Specifically, lanthanum more completely fills the lumen of the tubules and is denser than the peroxidase reaction product.

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Resolution, Contrast and Interpretation of HVEM Images of Crystals

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100071582 ◽

1973 ◽

Vol 31 ◽

pp. 228-229

Author(s):

L. E. Thomas ◽

J. S. Lally ◽

R. M. Fisher

Keyword(s):

High Voltage ◽

Chromatic Aberration ◽

Crystalline Materials ◽

Resolution Parameter ◽

Instrument Resolution ◽

Imaging Conditions ◽

Beam Excitation ◽

Optimum Imaging

In addition to improved penetration at high voltage, the characteristics of HVEM images of crystalline materials are changed markedly as a result of many-beam excitation effects. This leads to changes in optimum imaging conditions for dislocations, planar faults, precipitates and other features.Resolution - Because of longer focal lengths and correspondingly larger aberrations, the usual instrument resolution parameter, CS174 λ 374 changes by only a factor of 2 from 100 kV to 1 MV. Since 90% of this change occurs below 500 kV any improvement in “classical” resolution in the MVEM is insignificant. However, as is widely recognized, an improvement in resolution for “thick” specimens (i.e. more than 1000 Å) due to reduced chromatic aberration is very large.

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Radiation-Induced Precipitation at Thin Foil Surfaces in Ni-Be Alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100055217 ◽

1982 ◽

Vol 40 ◽

pp. 598-599

Author(s):

T. Mukai ◽

T. E. Mitchell

Keyword(s):

Electron Microscopy ◽

High Voltage ◽

Electron Irradiation ◽

High Vacuum ◽

Thin Foil ◽

Homogeneous Precipitation ◽

High Voltage Electron Microscopy ◽

Voltage Electron ◽

High Voltage Electron ◽

Radiation Induced

Radiation-induced homogeneous precipitation in Ni-Be alloys was recently observed by high voltage electron microscopy. A coupling of interstitial flux with solute Be atoms is responsible for the precipitation. The present investigation further shows that precipitation is also induced at thin foil surfaces by electron irradiation under a high vacuum.

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The Reduction of Chromatic Aberrations Due to Instrumental Instabilities

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100064128 ◽

1971 ◽

Vol 29 ◽

pp. 14-15

Author(s):

J. S. Lally ◽

R. Evans

Keyword(s):

Electron Microscope ◽

High Voltage ◽

Focal Length ◽

Chromatic Aberration ◽

Objective Lens ◽

Usual Practice ◽

Voltage Electron ◽

Short Focal Length ◽

Chromatic Aberrations ◽

Electron Microscopes

One of the instrumental factors often limiting the resolution of the electron microscope is image defocussing due to changes in accelerating voltage or objective lens current. This factor is particularly important in high voltage electron microscopes both because of the higher voltages and lens currents required but also because of the inherently longer focal lengths, i.e. 6 mm in contrast to 1.5-2.2 mm for modern short focal length objectives.The usual practice in commercial electron microscopes is to design separately stabilized accelerating voltage and lens supplies. In this case chromatic aberration in the image is caused by the random and independent fluctuations of both the high voltage and objective lens current.

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Some Biological Applications of High Voltage Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100051505 ◽

1974 ◽

Vol 32 ◽

pp. 298-299

Author(s):

Hans Ris

Keyword(s):

High Voltage ◽

Chromosome Structure ◽

Nerve Fibers ◽

Good Resolution ◽

High Voltage Electron Microscopy ◽

Voltage Electron ◽

University Of Wisconsin ◽

High Voltage Electron ◽

One Year ◽

The University

The High Voltage Electron Microscope Laboratory at the University of Wisconsin has been in operation a little over one year. I would like to give a progress report about our experience with this new technique. The achievement of good resolution with thick specimens has been mainly exploited so far. A cold stage which will allow us to look at frozen specimens and a hydration stage are now being installed in our microscope. This will soon make it possible to study undehydrated specimens, a particularly exciting application of the high voltage microscope.Some of the problems studied at the Madison facility are: Structure of kinetoplast and flagella in trypanosomes (J. Paulin, U. of Georgia); growth cones of nerve fibers (R. Hannah, U. of Georgia Medical School); spiny dendrites in cerebellum of mouse (Scott and Guillery, Anatomy, U. of Wis.); spindle of baker's yeast (Joan Peterson, Madison) spindle of Haemanthus (A. Bajer, U. of Oregon, Eugene) chromosome structure (Hans Ris, U. of Wisconsin, Madison). Dr. Paulin and Dr. Hanna are reporting their work separately at this meeting and I shall therefore not discuss it here.

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An Environmental Wet Cell For High Voltage Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100070539 ◽

1973 ◽

Vol 31 ◽

pp. 18-19

Author(s):

N.J. Tighe ◽

H.M. Flower ◽

P.R. Swann

Keyword(s):

Electron Microscopy ◽

High Temperature ◽

Image Quality ◽

Inelastic Scattering ◽

High Voltage ◽

High Voltage Electron Microscopy ◽

Voltage Electron ◽

Environmental Cell ◽

Water Saturated ◽

High Temperature Gas

A differentially pumped environmental cell has been developed for use in the AEI EM7 million volt microscope. In the initial version the column of gas traversed by the beam was 5.5mm. This permited inclusion of a tilting hot stage in the cell for investigating high temperature gas-specimen reactions. In order to examine specimens in the wet state it was found that a pressure of approximately 400 torr of water saturated helium was needed around the specimen to prevent dehydration. Inelastic scattering by the water resulted in a sharp loss of image quality. Therefore a modified cell with an ‘airgap’ of only 1.5mm has been constructed. The shorter electron path through the gas permits examination of specimens at the necessary pressure of moist helium; the specimen can still be tilted about the side entry rod axis by ±7°C to obtain stereopairs.

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A New 1000kv Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100062415 ◽

1969 ◽

Vol 27 ◽

pp. 100-101

Author(s):

J.L. Williams ◽

K. Heathcote ◽

E.J. Greer

Keyword(s):

Electron Microscope ◽

Direct Observation ◽

High Voltage ◽

Three Dimensional ◽

Dimensional Structure ◽

Specimen Thickness ◽

Voltage Electron ◽

High Voltage Electron Microscope ◽

Dynamic Experiments ◽

Conventional Instrument

High Voltage Electron Microscope already offers exciting experimental possibilities to Biologists and Materials Scientists because the increased specimen thickness allows direct observation of three dimensional structure and dynamic experiments on effectively bulk specimens. This microscope is designed to give maximum accessibility and space in the specimen region for the special stages which are required. At the same time it provides an ease of operation similar to a conventional instrument.

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